Sinn
Instrument Chronographs 917.010— lug 22mm

The lug width of the Sinn 917.010 is 22 millimetres. This measurement represents the distance between the axes of the two horizontal spring bars positioned beneath the case. It is critical to measure this correctly using a digital calliper: do not confuse lug width with the thickness of the case lug itself, which is narrower. All straps compatible with the 917.010 must have lugs dimensioned for 22mm.

Selection depends on intended usage. An alligator or vegetable-tanned calf strap is ideal for those who value aesthetics and desire a patina that evolves over time. A NATO strap in regenerated textile is perfect for daily operability and frequent style changes. Vulcanised rubber (FKM) represents the supreme technical solution if the chronograph is employed in humid environments or subject to contact with oils. For the 917.010, given its aeronautical heritage, the NATO maintains unequalled historical authenticity.

The 917.010 uses Sinn's patented bayonet lugs, which permit strap changes without specialised tools. Position the watch with the dial facing downward. Locate the two lateral metal tabs beneath the case (one on each side). Press gently toward the centre of the strap: the pin should slide laterally and disengage from its seating. Once the pin is extracted, the old strap separates completely. To mount the new 22mm strap, align the strap lugs with the case seating and insert the pin until you hear a slight engagement click.

Yes, absolutely. The 22mm lug width is a widely diffused standard in watchmaking, so numerous manufacturers produce compatible straps of excellent quality. Always verify that the strap has lugs dimensioned precisely at 22 millimetres and that the pins are compatible with the Sinn bayonet system. Straps in calf, alligator, NATO and rubber produced by specialised artisans often offer superior longevity and more controlled aesthetic evolution compared to maker's equivalents.

The lifespan of a leather strap depends on frequency of use, climatic conditions and material quality. A vegetable-tanned calf strap mounted on a 917.010 (a relatively heavy 44mm chronograph) has an average life of 3–4 years with daily wear, before stitching begins to fail or the material develops micro-lesions. Alligator, being more robust, easily reaches 5–6 years. Factors that reduce longevity include prolonged exposure to direct moisture, salty perspiration and UV exposure without protection. A vulcanised rubber strap, by comparison, can last 7–10 years owing to the absence of organic fibres and the chemical stability of the material.